Jmdonev: 1 revision imported

2018-05-11T18:17:08Z

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Jmdonev at 21:47, 9 May 2018

2018-05-09T21:47:50Z

← Older revision		Revision as of 21:47, 9 May 2018
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	[[Category:Done ~~2015~~-08-21]]		[[Category:Done 2018-04-30]]
	[[File:P-N Junction-1.png\|framed\|Figure 1. The p-n junction of a diode along with its corresponding schematic and real component.<ref name = "a">All About Circuits. (July 27, 2015). ''Introduction to Diodes and Rectifiers'' [Online]. Available: http://www.allaboutcircuits.com/textbook/semiconductors/chpt-3/introduction-to-diodes-and-rectifiers/</ref> The [[cathode]] and the [[anode]] of the diode are labelled so that [[conventional current]] flows from anode to cathode through the diode.]]		[[File:P-N Junction-1.png\|framed\|Figure 1. The p-n junction of a diode along with its corresponding schematic and real component.<ref name = "a">All About Circuits. (July 27, 2015). ''Introduction to Diodes and Rectifiers'' [Online]. Available: http://www.allaboutcircuits.com/textbook/semiconductors/chpt-3/introduction-to-diodes-and-rectifiers/</ref> The [[cathode]] and the [[anode]] of the diode are labelled so that [[conventional current]] flows from anode to cathode through the diode.]]

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	For more information about diodes, please see [http://www.allaboutcircuits.com/textbook/semiconductors/chpt-3/introduction-to-diodes-and-rectifiers/ all about circuits] or [http://hyperphysics.phy-astr.gsu.edu/hbase/solids/diod.html hyperphysics].		For more information about diodes, please see [http://www.allaboutcircuits.com/textbook/semiconductors/chpt-3/introduction-to-diodes-and-rectifiers/ all about circuits] or [http://hyperphysics.phy-astr.gsu.edu/hbase/solids/diod.html hyperphysics].

			== For Further Reading ==
			For further information please see the related pages below:
			*[[Diode]]
			*[[Direct current]]
			*[[AC to DC adapter]]
			*[[Photovoltaic cell]]
			*[[Electric current]]
			* Or explore a [[Special:Random\| random page!]]

	==References==		==References==
	{{reflist}}		{{reflist}}
	[[Category:Uploaded]]		[[Category:Uploaded]]

J.williams: 1 revision imported

2015-08-26T21:31:00Z

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Kjstenho at 20:50, 20 August 2015

2015-08-20T20:50:54Z

New page

[[Category:Done 2015-08-21]]
[[File:P-N Junction-1.png|framed|Figure 1. The p-n junction of a diode along with its corresponding schematic and real component.<ref name = "a">All About Circuits. (July 27, 2015). ''Introduction to Diodes and Rectifiers'' [Online]. Available: http://www.allaboutcircuits.com/textbook/semiconductors/chpt-3/introduction-to-diodes-and-rectifiers/</ref> The [[cathode]] and the [[anode]] of the diode are labelled so that [[conventional current]] flows from anode to cathode through the diode.]]

<onlyinclude>The way that a '''diode operates''' can be difficult to understand as it involves fairly advanced [[quantum mechanics]]. However, at the simplest level the operation of a [[diode]] can be understood by looking at the flow of positive charges (or "[[electron hole|hole]]s") and the negative charges (the electrons).</onlyinclude> Technically, a semiconductor diode is referred to as a '''p-n junction'''. These p-n junctions are important in the operation of a [[photovoltaic cell]] as well. Having the diode work properly requires a process known as [[doping]]. Semiconductors can be doped with materials so that they have an excess of easily displaced [[electron]]s - generally referred to as a '''negative''' or '''n-type''' region. As well, they can be doped with elements that create an excess of holes that easily absorb these electrons - generally referred to as a '''positive''' or '''p-type''' region.<ref>HyperPhysics. (July 27, 2015).''P-type Semiconductor'' [Online]. Available: http://hyperphysics.phy-astr.gsu.edu/hbase/solids/dope.html#c4</ref><ref>HyperPhysics. (July 27, 2015). ''N-type Semiconductor'' [Online]. Available: http://hyperphysics.phy-astr.gsu.edu/hbase/solids/dope.html#c3</ref> The negative and positive regions of the diode are also the component's [[cathode]] and [[anode]] respectively (see Figure 1).

The differences between these two materials and their interactions over very short distances (less than a millimeter) result in a diode when the two types are joined. Joining these two types creates the p-n junction, and the region between the two sides is called the depletion region, as electrons from the n-type region diffuse and fill some of the holes in the p-type region. This creates negative ions in the p-type region and leaves behind positive ions in the n-type region (see Figure 2).<ref>HyperPhysics. (July 27, 2015). ''Depletion Region'' [Online]. Available: http://hyperphysics.phy-astr.gsu.edu/hbase/solids/pnjun.html#c2</ref> This responds to electric fields differently depending on the direction of the electric field. This leads to useful electronic behaviour depending on which way the [[voltage]] (or [[electric field]]) is applied, this is called biasing.

==Bias==
A diode (PN junction) in an electrical [[circuit]] allows current to flow more easily in one direction than another. Forward biasing means putting a voltage across a diode that allows current to flow easily, while reverse biasing means putting a voltage across a diode in the opposite direction. The voltage with reverse biasing doesn't cause any appreciable current to flow. This is useful for changing [[AC]] current to [[DC]] current. It has other uses in manipulating electronic signals as well.

===Reverse Bias===
[[File:Reverse-Biased PN Junction.gif|framed|Figure 2. A reverse-biased p-n junction with the black circles representing easily displaced electrons and the white circles representing electron-deficient "holes." In a reverse-biased junction such as this, the electrons would leave the black circles and move toward the external circuit, leaving behind more positive ions, while electrons from the external circuit would "fill the holes," creating more negative ions.]]

If a [[voltage]] is applied across the diode in such a way that the n-type half of the diode was connected to the positive terminal of the voltage source and the p-type half was connected to the negative terminal, electrons from the external [[circuit]] would create more negative ions in the p-type region by "filling the holes" and more positive ions would be created in the n-type region as electrons are displaced toward the positive terminal of the voltage source (see Figure 2). Hence, the depletion region would increase and the voltage between the p-type and n-type regions would also increase as the total charge on each side of the junction increases in magnitude until the voltage across the diode equals and opposes the applied voltage and cancels it out, ceasing the current through the circuit. This process happens nearly instantaneously and results in essentially no current flow through the circuit when voltage is applied in this direction across the diode. This is known as a reverse-biased p-n junction.<ref>HyperPhysics. (July 27, 2015).''Reverse Biased P-N Junction'' [Online]. Available: http://hyperphysics.phy-astr.gsu.edu/hbase/solids/diod.html#c2</ref>

===Forward Bias===
[[File:Forward-Biased PN Junction.png|framed|Figure 3. A partially and fully forward-biased p-n junction. Note that a minimum voltage is required to collapse the depleted region.]]
When the voltage is applied in the opposite direction across the diode, the depletion region begins to shrink (see Figure 3). In a reverse-biased diode, the electrons and holes would be pulled away from the junction, but a forward-biased scenario ensures that the electrons and holes move toward the junction as they are repelled from the positive and negative terminals of the voltage source respectively.<ref name = "a"></ref><ref>HyperPhysics. (July 27, 2015). ''Forward Biased P-N Junction'' [Online]. Available: http://hyperphysics.phy-astr.gsu.edu/hbase/solids/diod.html</ref> Given a great enough applied voltage, both the holes and the electrons would overcome the depletion region and meet near the junction, where they could combine in a continuous process, closing the circuit and allowing current flow.

===Forward Voltage and Breakdown Voltage===
There is a minimum threshold voltage required to overcome the depletion region, which for most silicon diodes is a significant 0.7 [[volt]]s. Furthermore, reverse-bias voltage does induce a small amount of current through the diode called leakage current that is essentially negligible for most purposes. Finally, a great enough reverse voltage will result in the complete electronic breakdown of the diode and allow [[current]] to flow through the diode in the reverse direction.<ref name = "a"></ref>

For more information about diodes, please see [http://www.allaboutcircuits.com/textbook/semiconductors/chpt-3/introduction-to-diodes-and-rectifiers/ all about circuits] or [http://hyperphysics.phy-astr.gsu.edu/hbase/solids/diod.html hyperphysics].
==References==
{{reflist}}
[[Category:Uploaded]]

Diode operation - Revision history

Jmdonev: 1 revision imported

Jmdonev at 21:47, 9 May 2018

J.williams: 1 revision imported

Kjstenho at 20:50, 20 August 2015